Radio Access Network (RAN) sharing allows multiple operators to share the resources of a single evolved universal terrestrial radio access network (E-UTRAN) according to agreed resource allocation schemes. When these resources are shared they can be allocated unequally to the sharing operators, depending on the planned or current needs of these operators and based on service agreements with an owner of the E-UTRAN, which itself may be a sharing operator. For example, a given E-UTRAN may have a 40%/60% split for two sharing operators.
According to current RAN Sharing requirements defined by the Third Generation Partnership Project (3GPP), as defined in the 3GPP Standard technical specification, TS 22.101, resources should be allocated at the E-UTRAN per public land mobile network (PLMN) and, a sharing operator should be able to dynamically or semi-statically negotiate its quota in a cell level basis. For example, instead of a 40%/60%, an operator could request a 50%/50% split either always or during specific periods of the day for selected cells. There are currently no appropriate mechanisms to support this type of functionality due to several problems.
One problem is that current specifications only allow exchanging of cell resource utilization information between evolved node B (eNB) base stations on a per-cell basis. For load balancing purposes, a given cell is able to request its neighbor cells to provide their cell resource utilizations and get periodic reports when both cells are configured by the same mobile network operator. Therefore, current specifications do not allow for exchanging of cell resource utilizations on a per-sharing operator basis to neighbor base stations. This prevents load distribution and balancing to work correctly in the presence of sharing operators.
Another problem is that resource utilization measures, that could eventually trigger a quota re-configuration per sharing operator, are not reported on a per-sharing operator level of granularity to any centralized location so that decisions relating to quota re-configuration could be made. Also, there are currently no mechanisms allowing a sharing operator to optimally re-configure its quota in a shared RAN scenario. In a shared RAN scenario, the core network elements can either be per operator or shared. For example, if Long Term Evolution (LTE) is considered, the E-UTRAN resource utilization is only exchanged between base stations. Therefore, the E-UTRAN load is not reported to the mobile management entity (MME). The only load reporting procedures involving the base station and the core network, over the S1 interface, are the START OVERLOAD and STOP OVERLOADING procedures, where the MME may inform the base station about a signaling overload.
In a typical management system in 3GPP architecture, the node elements (NE), also referred to as base stations or as eNodesB in the case of E-UTRAN, are managed by a domain manager (DM), also referred to as the operation and support system (OSS). A DM may further be managed by a network manager (NM). Two base stations are interfaced by X2, whereas the interface between two DMs is referred to as Itf-P2P. The management system may configure the base stations, as well as receive observations associated with features of the network elements. For example, a DM observes and configures NEs, while an NM observes and configures a DM, as well as NEs via a DM.
In RAN sharing, different management architectures may exist. Thus, in some configurations, a shared E-UTRAN has a single DM and some of its functionalities, e.g., performance management (PM) may be accessed by multiple different Network Management Systems (NMSs) associated with each PLMN. In some configurations, each sharing operator can have its own Operation, Administration and Maintenance (OAM) capabilities, but, according to 3GPP specifications, information exchanges should be controlled by the hosting operator.
According to 3GPP specifications, selected OAM capabilities for the shared E-UTRAN, under the control of the hosting E-UTRAN operator, should be accessible by the sharing operator's OAM functions. This would allow, for example, the sharing operator to i) test the communication path between the sharing operator's network elements and the shared E-UTRAN, ii) obtain fault reports and iii) retrieve RAN resource usage information.
Two examples of network management architectures are shown in FIGS. 1 and 2, one with a shared core as in FIG. 1 and one with a common core as shown in FIG. 2. In each of FIGS. 1 and 2, two network management systems 10a and 10b, one for each public land mobile network (PLMN) for operators A and B, are in communication with a common domain manager 12 which is in communication with a base station 14 in which the resources of a cell of the base station are shared by the operators A and B. In FIG. 1, a core network element 16a, which could be a mobile management entity (MME) in a long term evolution (LTE) network, is provided for operator A and a core network element 16b is provided for operator B. In contrast, in the architecture of FIG. 2, a common core network element 18 is shared by operators A and B.
Resource utilization and/or load information may also be obtained at the Operations and Support System (OSS), e.g., by the downloading of reporting output period (ROP) files stored at the base station containing information from counters that measure the resource utilization as defined by the 3GPP in TS 32.425. As an example, the following counters have been defined:                4.5 Radio resource utilization related measurements        4.5.1 DL PRB Usage for traffic        4.5.2 UL PRB Usage for traffic        4.5.3 DL Total PRB Usage        4.5.4 UL Total PRB Usage        4.5.5 RACH Usage        4.5.5.1 Mean number of RACH preambles received        4.5.5.2 Distribution of RACH preambles sent        4.5.5.3 Distribution of RACH access delay        4.5.5.4 Percentage of contentious RACH attempts        4.5.5.5 Number of UE RACH reports received        4.5.5.6 Percentage of time when all dedicated RACH preambles are used        4.5.6 Cell Unavailable Time        4.5.7 TB related measurements        4.5.7.1 Total Number of DL TBs        4.5.7.2 Error Number of DL TBs        4.5.7.3 Total Number of UL TBs        4.5.7.4 Error Number of UL TBs        4.5.8 Power utilization measurements        4.5.8.1 Maximum carrier transmit power        4.5.8.2 Mean carrier transmit power        4.5.9 PRB Full Utilization        4.5.9.1 DL PRB full utilization        4.5.9.2 UL PRB full utilization        
According to 3GPP specifications in TS 32.425, all these measurements are performed at the cell level (EUtranCellFDD and EUtranCellTDD), so it is not possible to differentiate resource utilization measures per PLMN in a RAN Sharing scenario. The same can be said of other similar procedures in different technologies and over different interfaces, such as the Overload Start and Overload Stop procedures over S1; the Inter RAT RAN Information Management (RIM) based Cell Load Report; and similar procedures available for UTRAN technologies.
It is currently not possible to signal the load or resource utilization to any centralized network node, e.g., MME or OAM, so that this node is able to take resource re-allocation decisions per PLMN, i.e., re-configuring capacity quota per sharing operator. The existing granularity on a per-cell basis, either via S1 to the MME or to the OAM using existing counters, is not sufficient for control of resources, load and available capacity to be maintained on a per sharing operator basis.
A shared RAN may include a split between two (or more operators) as well as a commonly shared set of resources, e.g., 5% dedicated to operator A, 45% dedicated to operator B and 50% shared resources, as shown in FIG. 3. In FIG. 3, a RAN 20 has a first base station 14a and a second base station 14b serving cells 22a and 22b, respectively. Cells 22a and 22b serve user equipment (UE) 24a associated with operator A and UE 24b associated with operator B, respectively. A problem with the existing solutions is a lack of methods to negotiate and re-configure the resource quota to be assigned per sharing operator and on a per cell/network basis when one or multiple operators have a higher demand than their current quota per shared node. In summary, current specifications do not provide granularity higher than a per-cell basis for reporting of information that can help in determining load, resource utilization, and available capacity.